The present invention generally relates to an exterior rearview mirror assembly and, more particularly, to an exterior rearview mirror assembly that generates reduced wind noise.
Most, if not all, exterior rearview mirror assemblies create to varying degrees wind drag, which generates noise that can be heard in the interior of most vehicles. The threshold at which the noise becomes noticeable varies with the aerodynamic properties of the exterior of the mirror assembly, the speed of the vehicle on which the mirror assembly is mounted, and the insulation of the vehicle body. Another consequence of wind drag is decreased fuel economy which becomes more prevalent at higher speeds.
While some mirror assemblies incorporate folding mechanisms, such as break-away mechanisms and/or power-fold mechanisms, which permit, for example, the mirror casing to fold about the mounting portion, conventional vehicular exterior rearview mirror assemblies have a fixed angular orientation with respect to the vehicle for normal operating conditions. Break-away mechanisms permit the mirror casing or movable portion of the mirror assembly to fold against the vehicle when the movable portion is impacted with a force to thereby minimize damage to the mirror assembly when contact is made between the mirror assembly and an object. Power-fold mechanisms are commonly found in European vehicles and are provided to fold the mirror assembly against the side of the vehicle when the vehicle is parked to reduce the width of the vehicle. At lower speeds, the wind drag created by these fixed mirror assemblies may not be noticeable, but at elevated speeds, the noise level may be unacceptable.
Various attempts have been made to reduce the wind noise generated by exterior mirror assemblies. For example, structures have been incorporated into the exterior rearview mirror assembly housing to separate the airflow over the mirror assembly, which reduces turbulence of the airflow over the housing and, hence, reduces the noise. However, these structures are not aesthetically pleasing to some automobile manufacturers. Moreover, the cost of incorporating these various structures into the mirror assembly for some vehicles may be cost prohibitive.
Consequently, there is a need for a mirror assembly that exhibits reduced drag to thereby reduce the wind noise associated with the mirror assembly and, further, all in a manner that can minimize the cost of manufacturing the mirror assembly.